This Review showcases the ability of bi- and tridentate ligands to stabilize gold in high oxidation states through the formation of mono- and biscyclometalated gold(III) complexes. In-depth studies on the synthesis, intrinsic reactivity, catalytic relevance, and photophysical properties of stabilized gold(III) species have been carried out, setting the stage for exciting developments in various research areas, such as catalysis, inorganic and bioinorganic chemistry, ligand design, and materials science.

We report the design, synthesis, and application of a (N^C^C)-ligand framework able to stabilize highly electron-deprived gold(III) species. This novel platform enabled the preparation of C(sp(2))-gold(III) fluorides for the first time in monomeric, easy-to-handle, bench-stable form by a Cl/F ligand-exchange reaction. Devoid of oxidative conditions or stoichiometric use of toxic Hg salts, this method was applied to the preparation of multiple [C(sp(2))-Au(III)-F] complexes, which were used as mechanistic probes for the study of the unique properties and intrinsic reactivity of Au-F bonds. The improved photophysical properties of [(N^C^C)Au(III)] complexes compared to classical pincer (C^N^C)-Au systems paves the way for the design of new late-transition-metal-based OLEDs.

An efficient synthesis of biaryls through a gold-catalyzed oxidative cross-coupling of arenes with strong electron-deprived aryl boronates is presented herein. Regio- and chemocontrol are achieved by the selective activation of these coupling partners by gold at different oxidation states. Under reaction conditions devoid of basic additives or directing groups, the role of acetato ligand as an internal base has been revealed as a key parameter for expanding the reaction scope in these transformations.

The ubiquity of tertiary alkylamines in pharmaceutical and agrochemical agents, natural products and smallmolecule biological probes 1 , 2 continues to stimulate enormous efforts towards their streamlined synthesis 3 – 9 . Arguably, the most robust method for tertiary alkylamine synthesis is carbonyl reductive amination 3 : comprising two elementary steps, condensation of a secondary alkylamine with an aliphatic aldehyde forms an all alkyl-iminium ion, which is reduced by a hydride reagent. Chemists have sought to develop direct strategies for a ‘higher order’ variant of this reaction via the union of an alkyl fragment with an in-situ generated all alkyl-iminium ion 10 – 14 . However, despite more than 70 years of research, the successful realization of a ‘carbonyl alkylative amination’ has remained elusive. Herein, we report that a practical and general solution can be accomplished by the addition of alkyl-radicals to all alkyl-iminium ions. The process is facilitated by visible-light and a silane reducing agent, which, together with the other reaction components, trigger a distinct radical initiation step to establish a chain process. An attractive feature of this operationally straightforward, metal-free and modular transformation is the unbiased nature of tertiary amines that arise from the traceless union of aldehydes and secondary amines with alkyl-halides. As such, the structural and functional diversity within these classes of abundant feedstocks provides a versatile and flexible strategy for the streamlined synthesis of complex tertiary amines.

The underlying reactivity of Au-F species with aryl boronic acids has been studied in detail taking advantage of four novel, stable difluoro-[(C^N)AuF], arylmonofluoro-[(C^N)AuArF], and alkylmonofluoro-[(C^N)AuAlkF] gold(III) complexes, prepared and isolated in monomeric form. We provide the first experimental evidence for a direct Au-F/B transmetalation preceding the Csp-Csp or Csp-Csp bond formation.